ecs_ossl.c revision 296465
1/* crypto/ecdsa/ecs_ossl.c */ 2/* 3 * Written by Nils Larsch for the OpenSSL project 4 */ 5/* ==================================================================== 6 * Copyright (c) 1998-2004 The OpenSSL Project. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in 17 * the documentation and/or other materials provided with the 18 * distribution. 19 * 20 * 3. All advertising materials mentioning features or use of this 21 * software must display the following acknowledgment: 22 * "This product includes software developed by the OpenSSL Project 23 * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)" 24 * 25 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 26 * endorse or promote products derived from this software without 27 * prior written permission. For written permission, please contact 28 * openssl-core@OpenSSL.org. 29 * 30 * 5. Products derived from this software may not be called "OpenSSL" 31 * nor may "OpenSSL" appear in their names without prior written 32 * permission of the OpenSSL Project. 33 * 34 * 6. Redistributions of any form whatsoever must retain the following 35 * acknowledgment: 36 * "This product includes software developed by the OpenSSL Project 37 * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)" 38 * 39 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 40 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 41 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 42 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 43 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 45 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 46 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 48 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 49 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 50 * OF THE POSSIBILITY OF SUCH DAMAGE. 51 * ==================================================================== 52 * 53 * This product includes cryptographic software written by Eric Young 54 * (eay@cryptsoft.com). This product includes software written by Tim 55 * Hudson (tjh@cryptsoft.com). 56 * 57 */ 58 59#include "ecs_locl.h" 60#include <openssl/err.h> 61#include <openssl/obj_mac.h> 62#include <openssl/bn.h> 63 64static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dlen, 65 const BIGNUM *, const BIGNUM *, 66 EC_KEY *eckey); 67static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp, 68 BIGNUM **rp); 69static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len, 70 const ECDSA_SIG *sig, EC_KEY *eckey); 71 72static ECDSA_METHOD openssl_ecdsa_meth = { 73 "OpenSSL ECDSA method", 74 ecdsa_do_sign, 75 ecdsa_sign_setup, 76 ecdsa_do_verify, 77#if 0 78 NULL, /* init */ 79 NULL, /* finish */ 80#endif 81 0, /* flags */ 82 NULL /* app_data */ 83}; 84 85const ECDSA_METHOD *ECDSA_OpenSSL(void) 86{ 87 return &openssl_ecdsa_meth; 88} 89 90static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp, 91 BIGNUM **rp) 92{ 93 BN_CTX *ctx = NULL; 94 BIGNUM *k = NULL, *r = NULL, *order = NULL, *X = NULL; 95 EC_POINT *tmp_point = NULL; 96 const EC_GROUP *group; 97 int ret = 0; 98 99 if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL) { 100 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_PASSED_NULL_PARAMETER); 101 return 0; 102 } 103 104 if (ctx_in == NULL) { 105 if ((ctx = BN_CTX_new()) == NULL) { 106 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE); 107 return 0; 108 } 109 } else 110 ctx = ctx_in; 111 112 k = BN_new(); /* this value is later returned in *kinvp */ 113 r = BN_new(); /* this value is later returned in *rp */ 114 order = BN_new(); 115 X = BN_new(); 116 if (!k || !r || !order || !X) { 117 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE); 118 goto err; 119 } 120 if ((tmp_point = EC_POINT_new(group)) == NULL) { 121 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB); 122 goto err; 123 } 124 if (!EC_GROUP_get_order(group, order, ctx)) { 125 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB); 126 goto err; 127 } 128 129 do { 130 /* get random k */ 131 do 132 if (!BN_rand_range(k, order)) { 133 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, 134 ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED); 135 goto err; 136 } 137 while (BN_is_zero(k)) ; 138 139 /* 140 * We do not want timing information to leak the length of k, so we 141 * compute G*k using an equivalent scalar of fixed bit-length. 142 */ 143 144 if (!BN_add(k, k, order)) 145 goto err; 146 if (BN_num_bits(k) <= BN_num_bits(order)) 147 if (!BN_add(k, k, order)) 148 goto err; 149 150 /* compute r the x-coordinate of generator * k */ 151 if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx)) { 152 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB); 153 goto err; 154 } 155 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == 156 NID_X9_62_prime_field) { 157 if (!EC_POINT_get_affine_coordinates_GFp 158 (group, tmp_point, X, NULL, ctx)) { 159 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB); 160 goto err; 161 } 162 } else { /* NID_X9_62_characteristic_two_field */ 163 164 if (!EC_POINT_get_affine_coordinates_GF2m(group, 165 tmp_point, X, NULL, 166 ctx)) { 167 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB); 168 goto err; 169 } 170 } 171 if (!BN_nnmod(r, X, order, ctx)) { 172 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB); 173 goto err; 174 } 175 } 176 while (BN_is_zero(r)); 177 178 /* compute the inverse of k */ 179 if (!BN_mod_inverse(k, k, order, ctx)) { 180 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB); 181 goto err; 182 } 183 /* clear old values if necessary */ 184 if (*rp != NULL) 185 BN_clear_free(*rp); 186 if (*kinvp != NULL) 187 BN_clear_free(*kinvp); 188 /* save the pre-computed values */ 189 *rp = r; 190 *kinvp = k; 191 ret = 1; 192 err: 193 if (!ret) { 194 if (k != NULL) 195 BN_clear_free(k); 196 if (r != NULL) 197 BN_clear_free(r); 198 } 199 if (ctx_in == NULL) 200 BN_CTX_free(ctx); 201 if (order != NULL) 202 BN_free(order); 203 if (tmp_point != NULL) 204 EC_POINT_free(tmp_point); 205 if (X) 206 BN_clear_free(X); 207 return (ret); 208} 209 210static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dgst_len, 211 const BIGNUM *in_kinv, const BIGNUM *in_r, 212 EC_KEY *eckey) 213{ 214 int ok = 0, i; 215 BIGNUM *kinv = NULL, *s, *m = NULL, *tmp = NULL, *order = NULL; 216 const BIGNUM *ckinv; 217 BN_CTX *ctx = NULL; 218 const EC_GROUP *group; 219 ECDSA_SIG *ret; 220 ECDSA_DATA *ecdsa; 221 const BIGNUM *priv_key; 222 223 ecdsa = ecdsa_check(eckey); 224 group = EC_KEY_get0_group(eckey); 225 priv_key = EC_KEY_get0_private_key(eckey); 226 227 if (group == NULL || priv_key == NULL || ecdsa == NULL) { 228 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_PASSED_NULL_PARAMETER); 229 return NULL; 230 } 231 232 ret = ECDSA_SIG_new(); 233 if (!ret) { 234 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE); 235 return NULL; 236 } 237 s = ret->s; 238 239 if ((ctx = BN_CTX_new()) == NULL || (order = BN_new()) == NULL || 240 (tmp = BN_new()) == NULL || (m = BN_new()) == NULL) { 241 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE); 242 goto err; 243 } 244 245 if (!EC_GROUP_get_order(group, order, ctx)) { 246 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_EC_LIB); 247 goto err; 248 } 249 i = BN_num_bits(order); 250 /* 251 * Need to truncate digest if it is too long: first truncate whole bytes. 252 */ 253 if (8 * dgst_len > i) 254 dgst_len = (i + 7) / 8; 255 if (!BN_bin2bn(dgst, dgst_len, m)) { 256 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 257 goto err; 258 } 259 /* If still too long truncate remaining bits with a shift */ 260 if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) { 261 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 262 goto err; 263 } 264 do { 265 if (in_kinv == NULL || in_r == NULL) { 266 if (!ECDSA_sign_setup(eckey, ctx, &kinv, &ret->r)) { 267 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_ECDSA_LIB); 268 goto err; 269 } 270 ckinv = kinv; 271 } else { 272 ckinv = in_kinv; 273 if (BN_copy(ret->r, in_r) == NULL) { 274 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE); 275 goto err; 276 } 277 } 278 279 if (!BN_mod_mul(tmp, priv_key, ret->r, order, ctx)) { 280 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 281 goto err; 282 } 283 if (!BN_mod_add_quick(s, tmp, m, order)) { 284 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 285 goto err; 286 } 287 if (!BN_mod_mul(s, s, ckinv, order, ctx)) { 288 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 289 goto err; 290 } 291 if (BN_is_zero(s)) { 292 /* 293 * if kinv and r have been supplied by the caller don't to 294 * generate new kinv and r values 295 */ 296 if (in_kinv != NULL && in_r != NULL) { 297 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, 298 ECDSA_R_NEED_NEW_SETUP_VALUES); 299 goto err; 300 } 301 } else 302 /* s != 0 => we have a valid signature */ 303 break; 304 } 305 while (1); 306 307 ok = 1; 308 err: 309 if (!ok) { 310 ECDSA_SIG_free(ret); 311 ret = NULL; 312 } 313 if (ctx) 314 BN_CTX_free(ctx); 315 if (m) 316 BN_clear_free(m); 317 if (tmp) 318 BN_clear_free(tmp); 319 if (order) 320 BN_free(order); 321 if (kinv) 322 BN_clear_free(kinv); 323 return ret; 324} 325 326static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len, 327 const ECDSA_SIG *sig, EC_KEY *eckey) 328{ 329 int ret = -1, i; 330 BN_CTX *ctx; 331 BIGNUM *order, *u1, *u2, *m, *X; 332 EC_POINT *point = NULL; 333 const EC_GROUP *group; 334 const EC_POINT *pub_key; 335 336 /* check input values */ 337 if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL || 338 (pub_key = EC_KEY_get0_public_key(eckey)) == NULL || sig == NULL) { 339 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_MISSING_PARAMETERS); 340 return -1; 341 } 342 343 ctx = BN_CTX_new(); 344 if (!ctx) { 345 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE); 346 return -1; 347 } 348 BN_CTX_start(ctx); 349 order = BN_CTX_get(ctx); 350 u1 = BN_CTX_get(ctx); 351 u2 = BN_CTX_get(ctx); 352 m = BN_CTX_get(ctx); 353 X = BN_CTX_get(ctx); 354 if (!X) { 355 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 356 goto err; 357 } 358 359 if (!EC_GROUP_get_order(group, order, ctx)) { 360 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB); 361 goto err; 362 } 363 364 if (BN_is_zero(sig->r) || BN_is_negative(sig->r) || 365 BN_ucmp(sig->r, order) >= 0 || BN_is_zero(sig->s) || 366 BN_is_negative(sig->s) || BN_ucmp(sig->s, order) >= 0) { 367 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_BAD_SIGNATURE); 368 ret = 0; /* signature is invalid */ 369 goto err; 370 } 371 /* calculate tmp1 = inv(S) mod order */ 372 if (!BN_mod_inverse(u2, sig->s, order, ctx)) { 373 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 374 goto err; 375 } 376 /* digest -> m */ 377 i = BN_num_bits(order); 378 /* 379 * Need to truncate digest if it is too long: first truncate whole bytes. 380 */ 381 if (8 * dgst_len > i) 382 dgst_len = (i + 7) / 8; 383 if (!BN_bin2bn(dgst, dgst_len, m)) { 384 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 385 goto err; 386 } 387 /* If still too long truncate remaining bits with a shift */ 388 if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) { 389 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 390 goto err; 391 } 392 /* u1 = m * tmp mod order */ 393 if (!BN_mod_mul(u1, m, u2, order, ctx)) { 394 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 395 goto err; 396 } 397 /* u2 = r * w mod q */ 398 if (!BN_mod_mul(u2, sig->r, u2, order, ctx)) { 399 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 400 goto err; 401 } 402 403 if ((point = EC_POINT_new(group)) == NULL) { 404 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE); 405 goto err; 406 } 407 if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx)) { 408 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB); 409 goto err; 410 } 411 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == 412 NID_X9_62_prime_field) { 413 if (!EC_POINT_get_affine_coordinates_GFp(group, point, X, NULL, ctx)) { 414 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB); 415 goto err; 416 } 417 } else { /* NID_X9_62_characteristic_two_field */ 418 419 if (!EC_POINT_get_affine_coordinates_GF2m(group, point, X, NULL, ctx)) { 420 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB); 421 goto err; 422 } 423 } 424 425 if (!BN_nnmod(u1, X, order, ctx)) { 426 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 427 goto err; 428 } 429 /* if the signature is correct u1 is equal to sig->r */ 430 ret = (BN_ucmp(u1, sig->r) == 0); 431 err: 432 BN_CTX_end(ctx); 433 BN_CTX_free(ctx); 434 if (point) 435 EC_POINT_free(point); 436 return ret; 437} 438